The present invention relates to an apparatus for vacuum absorption and, more particularly, to an apparatus for vacuum absorption provided with an aspirator in a waterway wherein water is circulated by a pump.
There has formerly been an apparatus which utilizes an aspirator as a device to evacuate the inside of a vacuum vessel. The aspirator is provided with a inner tube, which tapers off toward the downstream end, in a hose. At the sidewall of the inner tube, a absorption passage connecting to the vacuum vessel is provided. That is, an accelerated speed of a stream by the inner tube makes a low pressure portion around the stream, and therefore the absorption passage can evacuate the inside of the vacuum vessel because the absorption passage is open to the low pressure portion.
FIG. 13 shows a conventional apparatus for vacuum absorption 53 provided with an aspirator 52 in a waterway 51 wherein a water is circulated by a pump 50. The apparatus for vacuum absorption 53 stores circulating water in a tank 54, and a one-way mechanism, which can be opened only when air is evacuated in a vacuum vessel 55, is provided in an absorption passage 56 of the aspirator 52 to which the vacuum vessel 55 is attached. Therefore, an atmospheric open valve 57 is separately provided to return an inside of the vacuum vessel 55 to an atmospheric pressure.
As for the one-way mechanism, the holes 58, 59 are not closed by a ball, or globe, 60 when fluid flows to the left direction in the drawing, as shown in FIG. 14(a), while the hole 58 is closed by the globe ball 60 under the influence of pressure of the fluid when the fluid flows to the right direction in the drawing, as shown in FIG. 14(b). The conventional apparatus for vacuum absorption 53 can maintain a vacuum in the vacuum vessel 55 by such a one-way mechanism provided in the absorption passage 56 even after the fluid stops in accordance with a stoppage of the pump 50.
But, when the inside of the vacuum vessel is required to return to the atmospheric pressure in the case of removal of the vacuum vessel 55 from the aspirator 52 or so, some other means are necessary and therefore an atmospheric open valve 57 is provided.
As mentioned above, since the conventional apparatus for vacuum absorption has an one-way mechanism, an atmospheric open valve and a control means accompanied therewith, there is a problem that the system of the conventional apparatus for vacuum absorption is large-scale. Therefore, an apparatus for vacuum absorption is required to omit the one-way mechanism and the atmospheric open valve, and to simplify the system. However, as shown in FIGS. 15 and 16, the following problems respectively occur when providing an outlet under or over a water surface in an apparatus wherein an one-way mechanism and an atmospheric open valve are omitted.
That is, as shown in FIG. 15, when the outlet 61 is provided under a water surface, an outbreak of noise by the collision of circulating water drained from the outlet 61 with the water surface and a reduction of absorption power of an aspirator 52 by involvement of air are not caused (refer to FIG. 15(a)). But, there is the problem that an unpleasant sound of sipping water occurs because the circulating water flows reversely into the vacuum vessel from the outlet and the water level in the tank 54 lowers to the position at a tip of the outlet 61 when the pump is stopped (refer to FIG. 15(b)).
On the other hand, when the outlet 61 is provided over the water surface, circulating water is not likely to be directed into the vacuum vessel 55 from the outlet 61 when the pump 50 is stopped (refer to FIG. 16(b)). But, there is the problem that the absorption power of the aspirator 52 reduces because air is directed into the tank 54 and a large quantity of bubbles are generated (refer to FIG. 16(a)). There is also the problem that noise breaks out because the drain water from the aspirator 52 collides with the water surface of the tank 54.
In view of the foregoing, it is therefore an object of the present invention to provide an apparatus for vacuum absorption which is quiet and simplified in the system thereof while maintaining an absorption power.